Allow a message for the Interrupt exception from SIGINT

Author: eregon

spec/ruby/core/exception/interrupt_spec.rb

@@ -29,7 +29,7 @@
       sleep
     rescue Interrupt => e
       e.signo.should == Signal.list["INT"]
-      e.signm.should == ""
+      ["", "Interrupt"].should.include?(e.message)
     end
   end
 end